With the emergence of new intracellular pathogens, such as Legionella
species, renewed interest has focused on the macrolide family of antib
acterials because of the ability of these drugs to penetrate cells. A
paradoxical situation exists regarding the clinical efficacy of macrol
ides and the poor serum concentrations achieved during therapy.;This m
ay reflect their excellent tissue penetration (particularly into infec
ted tissues), postantibiotic effects, and possible transport by phagoc
ytes. Moreover, macrolides exhibit various interactions with host defe
nce systems, including modification of phagocyte functions. Spiramycin
is a 16-membered-ring macrolide with an antibacterial spectrum charac
teristic of this class of drugs and including Gram-negative and Gram-p
ositive cocci, Parvobacteriaceae and some intracellular organisms; act
ivity against a number of parasites has also been demonstrated. Its ce
llular pharmacokinetics, postantibiotic effect and interactions with h
ost defence. systems appear to compare favourably with those of the ne
wer macrolides.